Bumping gaia.json for 2 gaia revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-central/rev/67cb3ced85f8
Author: David Flanagan <dflanagan@mozilla.com>
Desc: Merge pull request #21792 from davidflanagan/bug1037097

Bug 1037097: restrict image decode size in MediaFrame based on device memory size

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https://hg.mozilla.org/integration/gaia-central/rev/1986368a4663
Author: David Flanagan <dflanagan@mozilla.com>
Desc: Bug 1037097: restrict image decode size in MediaFrame based on device memory size

add unit tests
Bumping manifests a=b2g-bump